1. Field of the Invention
The present invention relates to a diaphragm for an acoustic device, and more particular to a vibration unit for an acoustic module, wherein the vibration unit comprises a suspension having a wavy configuration to ensure the vibration unit to be reciprocatingly moved in one direction for sound reproduction.
2. Description of Related Arts
A conventional acoustic device, such as a speaker, generally comprises a speaker frame, a vibration diaphragm supported by the speaker frame, a voice coil coupled at the vibration diaphragm, and a magnetic coil unit magnetically inducing with voice coil in order to drive the vibration diaphragm to vibrate for sound reproduction. In particular, the vibration diaphragm is mounted at an opening of the speaker frame, wherein when the voice coil is magnetically induced to reciprocatingly move, the vibration diaphragm is driven to vibrate correspondingly. However, the vibration direction of the vibration diaphragm is uncontrollable, such that the vibration diaphragm cannot reproduce good sound quality. In order to achieve better sound quality, the vibration diaphragm should only be reciprocatingly moved one direction with even amplitude. For example, when the vibration diaphragm is placed horizontally, the vibration diaphragm should only be reciprocatingly moved in a vertical (up-and-down) direction while the upward displacement of the vibration diaphragm should be the same as the downward displacement of the vibration diaphragm.
In order to enable the reciprocatingly movement of the vibration diaphragm, the vibration diaphragm comprises a suspension extended to the speaker frame as a surrounding of the vibration diaphragm. Accordingly, the suspension is made of elastic material and is formed in U-shape such that the suspension provides an elastic force to enable the vibration diaphragm to be reciprocatingly moved in response to the movement of the voice coil. However, the suspension not only allows the vibration diaphragm to move in a vertical direction, for example, but also unavoidably permits the vibration diaphragm to move in a lateral direction. Accordingly, the unwanted lateral movement of the vibration diaphragm will cause the unbalanced movement of the voice coil. Once the movement of the voice coil is not aligned with its center axis, the voice coil may scratch the inner side of the speaker frame. The protective coating of the voice coil will be gradually damaged. The peak of the suspension is upwardly protruded from a top side of the vibration diaphragm, such that the vibration diaphragm requires relatively larger space to incorporate with the suspension. The protruding portion of the suspension will be damaged easily by any external object.
Furthermore, due to the U-shaped cross section of the suspension, the upward displacement of the vibration diaphragm is not the same as the downward displacement thereof. In other words, the vibration diaphragm is not reciprocatingly moved in a linear manner. For example, when the suspension has the inverted U-shaped cross section, the upward displacement of the vibration diaphragm is larger than the downward displacement thereof. Especially for the acoustic device to generate the sound at low frequency, the vibration diaphragm requires relatively large amplitude to be reciprocatingly vibrated. In other words, the suspension will affect the sound reproduction at low frequency.
The size of the vibration diaphragm must be large enough to enable the vibration diaphragm to be vibrated via the suspension. In other words, the size of the speaker must provide enough installation space to hold the vibration diaphragm in position. Therefore, the structure of the speaker with this vibration diaphragm cannot be incorporated with any compact sized electronic device such as laptop, tablet, flat panel television, or mobile phone.